DESCRIPTION (adapted from the Abstract): CNS disorders are frequent sequelae of HIV infection. In addition to its direct effect upon infection of a variety of CNS cells, the HIV-1 may also exert its pathogenic effects by indirect mechanisms involving secreted cytokines and immunomodulators. In support of this concept, earlier studies by others and by the Principal Investigator have indicated that the viral regulatory protein, Tat, has the capacity to augment expression of tumor necrosis factor alpha (TNF-alpha), and transforming growth factor beta (TGF-beta) in cells from human and animal brain. The Investigator hypothesizes here that HIV-1 Tat, by de-regulating expression of these important cytokines, may contribute to CNS dysfunction. To examine the hypothesis, the Investigator plans to express Tat and its responsive cytokines, TNF-alpha and TGF-beta, in CNS cells, in vitro and in vivo, and to determine the ability of these proteins to cause alterations which are seen neuro-AIDS. The specific aims are to (1) construct a HSV1-based transduction vector which permits cell type-specific expression of foreign genes in single CNS cell types, and examine the level of its infectivity in a wide range of CNS cells and its fidelity for expressing the foreign gene in the designated CNS cell type in cell culture and animal model systems; (2) utilize the cell type-specific HSV-1 transduction system to express Tat, TNF-alpha, and TGF-beta in single CNS cell types and evaluate the pathological alterations caused by over-expression of these regulatory proteins in brain; (3) develop an inhibitory/therapeutic modality utilizing ribozymes to abrogate expression of Tat, TNF-alpha, and TGF-beta in animals experiencing CNS diseases as the result of over-expression of Tat, TNF-alpha, and TGF-beta, and determine the ability of these therapeutic agents to prevent or improve CNS disease manifestation. As proposed, the results of these studies will provide fundamental and detailed information regarding the role of cytokines induced by HIV-1 Tat in the CNS pathogenesis of AIDS and a wide range of other neurological disorders.